Eugene Klein (June 26, 1878 - April 30, 1944) was an internationally known stamp collector, stamp dealer, and auctioneer who was President of the American Philatelic Society from 1935 to 1937. Klein was the Official Expert of the American Philatelic Society from 1911 to 1931 and its International Secretary from 1928 to 1935 and 1937 to 1944. He also served as President (1935-1937) and International Secretary again from 1937 until his death. Wikipedia
The definitive Wikipedia entry for Eugene Klein. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Eugene_Klein_%28philatelist%29